Slovak Academy of Sciences

The magnetic field is an outstanding experimental tool for physics. To go beyond the conventional commercially available superconducting (SC) magnets, very large infrastructures such as the ones gathered within the European Magnetic Field Laboratory (EMFL) are necessary. The SuperEMFL project is a design study aiming at providing the European high field user community with much higher superconducting fields. This is meant to be achieved by combining high temperature superconductor (HTS) insert magnets, an emerging technology that can work in fields above 25T, with low temperature superconductor (LTS) outsert magnets, a technology limited to fields below 25 T. The project has two design magnetic field targets, 32+T and 40+T. The first design target proposed to combined a single stack of HTS pancakes in combination with a 19 T / 150 mm LTS magnet; the second either a similar arrangement at the sake of a narrower central space or a design with two nested HTS coils combined with a 15 T/ 250 mm LTS magnet. The particular choice of the project is to use no insulation but a metallic tape co-wound with the bare HTS tape. This so-called Metal as Insulation (MI) technology enables a self-protection feature of the HTS coil by allowing the electrical bypass of defects as well as better mechanical performances in a very compact winding. The use of HTS inserts introduces a change of paradigm by providing an unprecedented combination of high magnetic field and long measurement times whilst saving vast amounts of energy in operation.

• Multifunctional macromolecular phenolic antioxidants (HbPG-AoxAc) based on hyperbranched polyglycerol (HbPG) were synthesized. • Effective thermo- and photooxidative stabilization of LDPE and PP matrices by the HbPG-AoxAc macrostabilizers was observed. • Negligible leaching of the HbPG-AoxAc macromolecular additives was confirmed by hexane extraction tests. • Demonstrated potential for low-migration stabilization in advanced polyolefin applications. Multifunctional macromolecular antioxidants represent environmentally advantageous alternatives to conventional low molecular mass stabilizers for improving the long-term stability of polyolefins, such as polyethylene (PE) and polypropylene (PP), while minimizing additive migration in the surrounding environment. Hyperbranched macromolecules are especially promising for such purposes, due to their high number of functionalities, ease of production and limited migration. In this study, two hyperbranched polyglycerol (HbPG)-based antioxidants (HbPG-AoxAc) with different molar masses were synthesized by covalent attachment of sterically hindered phenolic units via esterification of the hydroxyl groups of HbPG. These macromolecular stabilizers were characterized by GPC, 1 H NMR and UV-Vis spectroscopies, confirming high antioxidant functionality and well-defined composition. Their performance in thermooxidative and photooxidative stabilization of LDPE and PP was systematically explored and compared with conventional low molecular mass stabilizers using chemiluminescence, oxidative induction time (OIT) determined by DSC, UV-Vis and FTIR spectroscopies. The obtained results indicate that the synthesized HbPG-AoxAc macromolecular antioxidants provide significant stabilization against both thermooxidative and photo-induced degradation in the polyolefin matrices, particularly in PP, and exhibit comparable efficiency to Irganox® 1010 and Irganox® HP-136, while outperforming the secondary antioxidant Irgafos® 168. Importantly, hexane extraction tests revealed negligible leaching of the macromolecular antioxidants, in sharp contrast to the extensive migration and loss observed for the low molecular mass reference additives. These findings confirm the potential of the HbPG-based macromolecular antioxidants as effective, low-migration additives for advanced and environmentally friendly polyolefin applications.

Abstract. The Moderate Resolution Imaging Spectroradiometer (MODIS) is one of the most attractive remote sensing datasets used for mapping snow cover. The MODIS product is expected to be replaced by the Visible Infrared Imaging Radiometer Suite (VIIRS) snow cover product in the near future. Therefore, a reliable and accurate evaluation of this product is needed for future hydrological applications. This study aims to assess the mapping accuracy of the VIIRS snow product at the regional scale (i.e., at 631 climate stations in Austria) and within a small experimental catchment, the Jalovecký Creek catchment in northern Slovakia, using extensive snow course measurements conducted at both open and forested sites between January 2012 and December 2020. In the VIIRS snow cover product, the Normalized Difference Snow Index (NDSI) is used to detect snow. A threshold of NDSI (TNDSI) is needed for distinguishing snow from snow-free land. Based on the daily snow depth observations from climate stations/snow course locations, the optimal NDSI threshold (OTNDSI) is first determined through a detailed sensitivity test (100 different TNDSI from 1 to 100 with a step of 1). The overall accuracy (OA) of VIIRS data is then evaluated based on the OTNDSI. The assessment of the OTNDSI/OA is performed for all climate stations/snow profiles, as well as for different groups of stations/snow profiles representing different physiographic and land cover conditions. The findings demonstrate that the classification accuracy for 631 Austrian stations using the optimal thresholds ranges from 52.3 % to 99.3 %, with a median of 92.5 %. The NDSI thresholds vary seasonally and decrease with increasing elevation. The NDSI thresholds fitted to different months and elevations show the smallest differences to OTNDSI in overall accuracy. The NDSI thresholds fitted to different elevations improve regional snow cover mapping by 1.5 % between 900 – 1200 m a.s.l. and by 3.1 % above 1200 m a.s.l. At the catchment scale, the difference is found between open and forested sites, where the mapping accuracy is lower in the forest. VIIRS enables snow mapping accuracy from 71.5 to 95.9 % at the open site (during winter, median OA is up to 98.8 %) and from 58.1 to 93.7 % at the forest site (during winter, median OA is up to 91.5 %). The overall accuracy at the site with the most measurements is 95.9 % (Červenec – open site) and 93.7 % (Červenec – forest site), respectively. The accuracy at the forest is more sensitive to seasonal variation compared to the open area, where the accuracy is more stable and accurate across the year.

Historical disposal of acid tars from Petrochema refinery operations has resulted in persistent environmental hazards arising from the open acid-tar lagoons. These lagoons accumulate strongly acidic, highly contaminated waters enriched with organic compounds and heavy metals, posing significant risks of overflow and contamination of surrounding soils and groundwater. To mitigate these risks, electrochemical advanced oxidation using boron-doped diamond electrodes (BDD) was investigated as a treatment method for the contaminated surface water. Laboratory experiments demonstrated progressive degradation of organic pollutants, with chemical oxidation demand (COD) and total organic carbon (TOC) reductions of up to 94 % after four hours. Sulfonated compounds were oxidatively cleaved, releasing sulfate ions, while oxalate formed as a transient intermediate before complete conversion to CO2 and water. Instantaneous current efficiencies reached ~90 % and specific energy consumption 25 kWh per kg of COD removed in the initial current-limited stage, decreasing at higher currents due to mass transport limitations and side reactions. These results highlight the potential of electrochemical oxidation to achieve near-complete mineralization of persistent organics, and provide a sustainable solution for the remediation of acid-tar-contaminated waters at legacy industrial sites.

Leucine is an essential amino acid which is imported into the brain parenchyma with high capacity. Animal studies have demonstrated that leucine plays a significant role in several cellular and physiological processes in brain parenchyma. In addition to its role in protein synthesis, leucine possesses signaling and regulatory functions. Furthermore, leucine catabolism may provide brain cells with amino nitrogen for the synthesis of glutamate and glutamine with an impact on sustaining glutamatergic and GABA-ergic neurotransmission. The entry of leucine's carbon skeleton into the intermediary metabolism of astrocytes yields the production of ketone bodies and acetyl-CoA. In order to investigate the metabolic capabilities of human astrocytes regarding leucine, we enriched their culture media with 13C₆,15N-leucine and conducted a metabolomic study using liquid chromatography-mass spectrometry (LC-MS) to identify and quantify isotopically labelled metabolites. Furthermore, we employed an antiserum against 3-methylcrotonyl-CoA carboxylase (MCC), the unique enzyme in the irreversible phase of leucine catabolism, to identify MCC-expressing cells both in culture and in situ. Our results indicate that cultured human astrocytes efficiently removed leucine from the medium, which was then enriched with several compounds containing nitrogen and/or carbon atoms derived from leucine. Among the released metabolites, glutamine and citrate were the most abundant. Leucine uptake was independent of glucose concentration; however, hyperglycemic conditions stimulated the capacity for the irreversible catabolism of the leucine-derived carbon skeleton. Immunoprobing with the MCC antiserum confirmed the mitochondrial expression of MCC in astrocytes in culture as well as in situ. In addition to astrocytes, immunofluorescent double-labelling revealed the colocalization of MCC with a neuronal marker in human brain sections. This study confirms that human astrocytes are capable of catabolizing leucine and incorporating leucine-derived atoms into the intermediary metabolism. The presence of MCC in cultured astrocytes underscores their ability to convert leucine into acetyl-CoA and ketone bodies. Additionally, MCC expression in astrocytes and neurons present in brain parenchyma suggests that these cells are enzymatically equipped to catabolize leucine into compounds entering their cellular metabolism.

Standard Fourier transfer function (modulus of the complex Fourier transfer function) is widely accepted and used for both theoretical/numerical analyses and analyses of real recordings, especially for identifying resonance peaks and/or the amplified frequency bands. This is because it characterizes (linear, time-invariant) transfer properties of the medium between a source and receiver in the frequency domain. Being, however, just an amplitude Fourier spectrum of the time-domain impulse response, it cannot alone provide any information on temporal development of the response, that is, the temporal distribution of the different reverberations that cause amplifications, and therefore on their origin.However, it is reasonable to assume that the missing information could be useful for interpreting complicated resulting motions in local surface structures because they are often due to multiple wave reflections and transmissions, conversions, interference, diffraction, scattering and resonance.Therefore, we introduce a new tool for analysing seismic response including its temporal development – a time-frequency transfer function, TFTF, based on the continuous wavelet transform of the impulse response. Modulus of TFTF provides information on the temporal development of frequency-dependent amplification and its duration, linking amplified frequency bands to specific arrivals and reverberation trains rather than to spectral peaks alone.We present numerical examples for several sedimentary structures close to pure 1D layers, proving that TFTF is much more informative than the standard Fourier transfer function: in particular, it allows to identify late arrivals and long-lasting reverberations, providing a deeper insight on their physical origin.

Abstract Background and aims Antimony (Sb) is an emerging ecosystem pollutant due to increasing industrial activity, traffic, and ongoing military activity in various regions of the world. Very little is known about the intraspecific variation of crop responses to this hazardous metalloid; therefore, we compare the response of two maize hybrids to elevated Sb. Methods Two maize ( Zea mays L.) hybrids (Luciana and Tweetor), differing in their resistance to other abiotic stressors, were exposed to various doses of Sb (0, 25, and 50 mg L −1 Sb) in hydroponics. Plant production parameters and Sb uptake have been investigated. Stress markers and metabolites, along with the changes in root tissue development, were analysed. Additionally, root cell viability, ROS accumulation, and activity of selected antioxidants have been investigated. Results Both hybrids exhibited dose-dependent adverse effects of Sb exposure, including changes in root growth, anatomy, and biochemical parameters. The hybrid Tweetor showed higher Sb accumulation in roots and lower root biomass than the hybrid Luciana. Root-to-shoot Sb translocation differed between the hybrids and was in correlation with the development of root apoplasmic barriers. Furthermore, differences among maize hybrids were observed in free radical production and antioxidant defense system activity. Conclusion Our experiments revealed novel findings indicating that intraspecific variability in Sb uptake plays a crucial role in hybrid-specific tolerance mechanisms to antimony stress. Moreover, the results of this study highlight and underscore the practical importance of proper hybrid selection for the cultivation of crops in soils contaminated by toxic metalloids, such as Sb, which is of great concern for the future.